SOLEDAD O'BRIEN, HOST: This is Blacksburg, Virginia, a town of about 40,000 people nestled in the shadows of the Blue Ridge Mountains. It's an area that's been ranked one of the best places to live in America, a community where crime is rare. It's where grandparents go to retire, where parents send their children off to school.

Blacksburg is a college town, and that college is Virginia Tech.

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O'BRIEN (voice-over): More than 26,000 students from every state and more than 100 countries call this school home. It's known for its engineering and agricultural programs, a state research university spread over 2,600 acres of rolling Virginia countryside.

UNIDENTIFIED MALE: There's no crime here. The local news doesn't have much to report because not much happens as far as crime or anything like that. We don't lock our doors here.

O'BRIEN: Monday was scheduled to be a busy day at Virginia Tech. There was an art exhibit at the Alumni Center, an African student union luncheon at the International Center, and anticipation was building for this weekend when the Hokies' nationally ranked football team would play its annual spring game. It was the beginning of a new school week on campus where spring had not quite yet sprung. But Monday, April 16, would be no ordinary day.

UNIDENTIFIED MALE: At about 7:15 this morning, a 911 call came to the university police department concerning an event in West Ambler Johnston Hall. There were multiple shooting victims.

O'BRIEN: Matt Lewis and Matt Green of the campus EMT service were on duty. Their unit was one of the first on the scene.

MATT LEWIS, VIRGINIA TECH CAMPUS EMT: Well, the first call came out for a patient who had fallen out of a loft. And once they got on scene, they noticed that there were two patients with gunshot wounds.

O'BRIEN (on camera): At point, can you tell us if the victim was alive?

LEWIS: Both patients were at that time.

O'BRIEN (voice-over): Police began sweeping the dormitory. The gunman was still on the loose.

WENDELL FLINCHUM, VIRGINIA TECH POLICE CHIEF: It was an isolated event to that building and the decision was made not to cancel classes at that time.

O'BRIEN: Classes had been disrupted three days earlier after a bomb threat, but this time, no false alarm. The shooting left two students dead: 19-year-old Emily Hilscher, a freshman majoring in animal and poultry sciences, and 22-year-old Ryan Clark. His friends called him Stack. He was a resident adviser and played in the marching band. As an R.A., his job was to look at students and his friends speculate he may have been caught in the crossfire.

SHADIE TANIOUS, FRIEND: As an R.A., and a good person, he apparently was going to break up an argument or something like that and wrong place, wrong time. That's kind of hard to think about.

O'BRIEN: At first, police believe the shooting was a domestic dispute, a romance gone horribly wrong. Their chief suspect, Emily's boyfriend, Carl Thornhill who attended college nearby and was said to own guns. Investigators related all this to university administrators. By then, morning classes were underway, and Virginia Tech president Charles Steger saw no need to cancel them.

CHARLES STEGER, PRESIDENT, VIRGINIA TECH: The situation was characterized as being confined to that dormitory room. We thought we had it under control.

O'BRIEN: Thornhill would be held all day then released. So students and faculty weren't told about the shootings. It was business as usual. Engineering student, Ryan Brody, had to be at work at 9:00 a.m.

RYAN BRODIE, ENGINEERING STUDENT, VIRGINIA TECH: I woke up and checked my e-mails because of the bomb threats that we had Friday and the buildings were being closed. So I checked the website and checked the e-mail and there was nothing in there. So I went to work.

(on camera): Friends say that at about ten minutes of 9:00, Erin Peterson (ph) and Reama Samaha (ph) would be making their way out of their dorm room straight through this tunnel and off to French class in Norris Hall. The two are friends. They went to high school together and lived next door to each other in the dorm. And the fastest way to class was straight across the drill field.

(voice-over): 9:26 a.m., more than two hours after the shooting, a campus-wide e-mail was finally sent out notifying students and faculty. The e-mail urged caution, told students to call police with anything suspicious. But Reama (ph) and Erin (ph) French class was already under way. Was it too little too late?

STEGER: I don't think anyone could have predicted that another event was going to take place.

O'BRIEN: But it did. By 9:46, there's a hail of gunfire in Norris Hall. Coming up, the killer strikes again.

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O'BRIEN (voice-over): 9:45 a.m., more gunshots are heard.

UNIDENTIFIED MALE: How many shots do you exactly recall hearing?

UNIDENTIFIED MALE: It was at least 30 to 40.

O'BRIEN: This time the shots came from Norris Hall Engineering Building.

(on camera): The very first pictures we see come from right here where people are now diving behind these pillars to stay safe. Up on the second floor you could hear the gunfire. People are scrambling inside to get out any way they can. Those who try to get down the stairs discovered chained doors.

UNIDENTIFIED FEMALE: Right after we got that e-mail, we heard five shots from campus. And we could hear the emergency speaker system.

UNIDENTIFIED MALE: This is an emergency, this is an emergency.

UNIDENTIFIED FEMALE: So we all got down underneath the desks and moved away from the windows.

O'BRIEN: More images of the shooting captured by two Swedish exchange students who had just arrived the night before.

9:50 a.m., the university sends a second campus-wide e-mail warning of a gunman on the loose. Units from three police departments rush to Norris Hall.

NICK MALCO, WITNESSED SHOOTING: And we hear this loud sound out in the hallway. It was just bang, bang, bang, bang out in the hallway and you don't really recognize what it is at all. It's just kind out of place on campus.

ERIN SHEEHAN, WITNESSED SHOOTING: He just stepped in five feet from the door and started firing. He seemed very thorough about it.

MALCO: Not five, 10 seconds later, he tried to come into our room and tried to shove the door open. And at that point, we were like, OK, this is very, very serious, and he shot the door twice. We heard him reload outside and shot the door again and then just continued on.

O'BRIEN: 10:17, a third e-mail, this time ordering a campus lockdown.

BRODIE: They told us to stay inside. The gunman is on the loose on campus. He's still at large and to stay in any buildings, or wherever you are, stay away from doors and windows, to try to keep everybody safe and to keep him from being attracted to other buildings.

REBECCA MACDANIEL, STUDENT, VIRGINIA TECH: They locked all of us in the bookstore and kept us in the center of the bookstore.

STEGER: Upon arrival to Norris, the officers found the front doors barricaded. Within a minute, the officers breached the doors which had been chained shut from the inside. Once inside the building, the officers heard gunshots. They followed the succession of gunshots to the second floor. Just as officers reached the second floor, the gunshots stopped. The officers discovered the gunman who had taken his own life.

O'BRIEN: Police discovered the gruesome crime scene, students and faculty, dead, in four classrooms and in a stairway. The wounded were carried outside to emergency medical teams.

SARAH WALKER, EMT: There were five very seriously injured people in front of me and they needed to get out and they were my priority.

O'BRIEN: One of the injured was Emily Haas. Two bullets grazed her head.

EMILY HAAS, SHOOTING VICTIM: When I got hit, I felt it, and I didn't know if I was hurt, if I was shot, and I did try to keep really still and hoping that he would think I was already dead.

O'BRIEN: 12:22 p.m., university officials announce the campus was secured. But still the enormity of the tragedy was still not clear.

FLINCHUM: We have a ballpark figure on the fatalities. It's at least 20 fatalities.

GRIFFON: It was crazy to me, like, first you hear one person dead, then seven, eight persons injured, then 10 people injured.

O'BRIEN: By late afternoon, the death toll had grown.

STEGER: It is now confirmed that we have 31 deaths from the Norris Hall, including the gunman. There are two confirmed deaths from the shooting in Ambler Johnston dormitory in addition to the 31 at Norris Hall.

O'BRIEN: A staggering loss of life.

NATE WILLIAMS, STUDENT, VIRGINIA TECH: You know nobody woke up Monday morning expecting to go to class, you know, for a killer, you know, to walk in with two guns and shoot them down, shoot friends down, wound, you know, loved ones. Nobody expected that. O'BRIEN: Joseph Samaha watched the breaking news on television from his home, fearing for his 18-year-old daughter, Reama (ph).

JOSEPH SAMAHA, FATHER OF VIRGINIA TECH STUDENT: That's the first thing I was worried about when she didn't return the call. She didn't pick up. But I'm a person that always tends to prepare for both good and bad. And as the hours went on, the minutes went on; I knew it wasn't going to be good.

O'BRIEN: For eight long hours, this close-knit college community had gone through hell while the world looked on. In Washington, the president addressed the nation.

GEORGE W. BUSH, PRESIDENT OF THE UNITED STATES: We hold the victims in our hearts. We lift them up in our prayers and we ask a loving God to comfort those who are suffering today.

O'BRIEN: The media descended on Blacksburg. There were many questions, but the answers were incomplete at best.

FLINCHUM: We're still waiting for the lab results to come back. There's a lot of work to be done yet.

STEGER: We'll decide that tomorrow probably.

O'BRIEN: Tuesday morning, we learned more about the victims. Joe Samaha's fears were realized, his daughter Reama (ph) was dead.

SAMAHA: She loved people, she loved life, and she loved what she chose to do and it was dance and language and travel and that's what she came to tech to do.

O'BRIEN: Her friend and dorm mate Erin Peterson (ph) died with her.

UNIDENTIFIED FEMALE: She always put a smile on people's face, like, she was just so cheerful.

O'BRIEN: Senior Leslie Mel, who overslept that morning, never made it to her class in Norris Hall.

MEL: It's hard that this is going to be my last memory of Virginia Tech. I mean, fortunately for everyone else, you have time here, and you have time to make the best of what's left, and cover up these memories with new ones and rebuild from where we are today. But I just -- my heart goes out to everyone else who's graduating who this is the last thing that they're really left with.

O'BRIEN: The grieving process began, but who did this, and why? So far, only one partial I.D., the Norris Hall shooter was an Asian male. Some on campus weren't surprised who it was, Cho Seung-Hui.

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(BEGIN VIDEOTAPE) O'BRIEN (on camera): As news of the shooting began to trickle out, the speculation was rampant. What kind of a madman would enter a classroom, like this one, shoot at students who were sitting at their desks, kill a teacher in the front of the room, and then move on to another classroom? But when the identity was finally revealed, there were many people who were not surprised.

UNIDENTIFIED MALE: At 9:29 Tuesday mortgage, the name whispered among students and teachers now becomes known to the world.

FLINCHUM: That person is Cho Seung-Hui. He was a 23-year-old South Korean here in the U.S. as a resident alien.

UNIDENTIFIED MALE: There is no shock, no stories about the nice, clean-cut kid next door. Looking back, many should have seen this coming, though some who knew him did. Cho Seung-Hui, his psychotic tapes in the mail heading to New York had been sending out warning signals for years.

NIKKI GIOVANNI, POET,AUTHOR & PROFESSOR: I just didn't think he was disturbed as we would normally think of a kid as disturbed. I thought he was mean.

UNIDENTIFIED MALE: Two years ago, poet, author, professor, Nikki Giovanni taught Cho poetry until she just couldn't take him anymore.

GIOVANNI: I couldn't be in a classroom with a kid I can't control. I don't know how else to say that.

UNIDENTIFIED MALE: Giovanni says he attended class wearing dark glasses. He would not participate, would not answer when called on. Secretly, he was taking pictures of other students. His writings were dark, angry, sickening -- "Must kill Dick, Dick must die." Other parts of this play can only be described as violently pornographic.

Giovanni said her other students were scared, so was she. She told the English Department Cho had to leave.

GIOVANNI: Mr. Cho has to come out of my class or I'm going to resign.

LUCINDA ROY, CHAIR OF ENGLISH DEPARTMENT, VIRGINIA TECH: I took him out of class and taught him myself. Then I made it clear that that kind of writing wouldn't be acceptable and he...

UNIDENTIFIED MALE: Lucinda Roy was the English Department chair. She took over teaching Cho one on one until she realized his writings weren't just dark ramblings. Cho was a threat.

ROY: So I would go to police and to counselors and to student affairs and everywhere else, and they would say, there's nothing explicit here. He's not actually saying he's going to kill someone. And my argument was he seemed so disturbed anyway that we needed to do something about this.

UNIDENTIFIED MALE: Classmates openly discussed whether Cho would become a school shooter. Now we know he may have been thinking the same thing.

UNIDENTIFIED MALE: At 8 years old, Cho and his family left South Korea and moved to the suburbs of Washington, D.C. In Chantilly, Virginia, he and his older sister attended Westfield High School while their parents built a dry cleaning business. His family, painfully shy and now horrified, remain secluded. But in Korea, a great-aunt says that even as a young boy, Cho was odd.

UNIDENTIFIED FEMALE (through translator): From the beginning, he wouldn't answer me. Cho doesn't talk. Normally sons and mothers talk. There was none of that for them. He was very cold.

UNIDENTIFIED MALE: He graduated high school in 2003 without a single friend. That wall now on the campus of Virginia Tech, Cho referred to himself by the name Question Mark and used the symbol when signing into class. To his roommates, he really was a question mark.

UNIDENTIFIED MALE: We tried to hang out with him at first, took him, introduced him to our friends and stuff. And weeks of this and he never opened up, just never talked to us and went about his day by himself, never saw anyone come visit him.

UNIDENTIFIED MALE: Andy and John, they don't want to give out their last names, shared a small dorm suite with Cho in the fall of 2005 but never really knew him.

UNIDENTIFIED MALE: He never talked to me. He never got up and closed the door himself. And he never turned off the lights when he was going to bed.

UNIDENTIFIED MALE: They just thought he was odd, quiet, until that night in November of 2005 when they came home and found university police at their door. Cho had been stalking a female student.

UNIDENTIFIED MALE: I heard he started talking to her online first. He found where she lived, started talking to her on AIM, then he went over there and was using the name Question Mark. He said, "Hey, I'm Question Mark," and that really freaked the girl out.

UNIDENTIFIED MALE: Police found no evidence of an imminent threat, but weeks later they were back. Cho Seung-Hui was stalking again.

UNIDENTIFIED MALE: The cops responded again and Seung became upset about that. And he had told me that he might as well kill himself. And so I told the cops that and they took him away to the counseling center for a night or two.

UNIDENTIFIED MALE: What happened next will forever haunt the parents, the friends, the brothers and sisters of those Cho killed. In a phrase, his case was swept clean. On December 13, 2005, a judge ruled Cho mentally ill, an imminent danger to himself, and ordered his temporary detention. Facing involuntary commitment and a record, Cho agreed to be taken to a mental health facility for further evaluation. Once Cho agreed to get help, his treatment became a private matter. According to law, not even the university would know.

DR. CHRIS FLYNN, COUNSELOR, VIRGINIA TECH: The university is not part of the mental health system, nor the judiciary system, and we would not be the providers of mandatory counseling in this instance.

UNIDENTIFIED MALE: Fourteen months later, Cho walked into this pawnshop near campus and filled out the instant background check needed to purchase a gun. The stalking complaints, the suicide warning, the mental illness ruling, none of it would make its way to the criminal databases that would prevent the purchase. In the eyes of the law, this twisted killer, this silent and scary roommate, this macabre author had a legal right to purchase a weapon. Two months before firing a single shot, Cho was already walking a well-worn path.

When we come back, the mental journey of a mass murderer.

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O'BRIEN (on camera): Here on the campus of Virginia Tech, many people wonder how Cho Seung-Hui's grievance, whether they were real or imagined, could build to such a rage that would finally be unleashed here at Norris Hall. What made him different from people who think about revenge but never act? Is there a profile of a mass murderer that could help prevent future tragedies?

CHO SEUNG-HUI, VIRGINIA TECH GUNMAN: You had a hundred billion chances and ways to have avoided today, but you decided to spill my blood.

UNIDENTIFIED MALE: He wrote about his grievances.

CHO: You just love to crucify me.

UNIDENTIFIED MALE: He blamed other people.

CHO: You forced me into a corner and gave me only one option. The decision was yours.

UNIDENTIFIED MALE: He said, "You caused me to do this."

CHO: Now you have blood on your hands that will never wash off.

UNIDENTIFIED MALE: That is the mindset of a mass murderer.

O'BRIEN (voice-over): Understanding the mindset of people like Cho Seung-Hui is key to preventing future attacks, which is why the U.S. Department of Education and the Secret Service, which identifies potential threats to the president, published a 2002 study of school shootings. There had been a string of incidents: Pearl, Mississippi; Paduka, Kentucky; Jonesboro, Arkansas.

WILLIAM MODZELESKI, U.S. DEPARTMENT OF EDUCATION: It seemed like every other month there was another school shooting that was occurring in the country. O'BRIEN: Then on April 20, 1999, two students at Columbine High School in suburban Littleton, Colorado, killed 12 classmates and a teacher and wounded 23 others.

UNIDENTIFIED FEMALE: And then he came into the library and shot everybody around me, then put a gun to my head and asked if we all wanted to die.

O'BRIEN: But after analyzing school shootings from the preceding 25 years, the study group found no clear profile.

MODZELESKI: We saw kids who were doing well academically, some kids who weren't doing well academically. Some kids who were doing well socially, some kids that weren't doing well socially. Some kids that were in the high end of a socio-economic strata and kids who were at the low end of the socio-economic strata. So it's very difficult to develop a profile.

O'BRIEN: What they and other experts have found is a syndrome of stress, depression and rage.

DEWEY CORNELL, UNIVERSTITY OF VIRGINIA: It starts with them feeling like they've been rejected, like they aren't recognized as human beings, and then in response, they treat others in the same way.

O'BRIEN: The process usually starts with some type of grievance and a sense of persecution. In schools, it's often about being bullied. Eric Harris and Dylan Klebold's rampage at Columbine is the classic case.

CORNELL: These boys wrote essays in which they described standing up to bullies and shooting them.

UNIDENTIFIED MALE: Do not mess with that frigging kid!

CORNELL: They made videotapes in which they enacted this fantasy of taking revenge on everyone around them.

O'BRIEN: Feeling powerless but wanting control is also a common factor when massive violence erupts on the job.

UNIDENTIFIED MALE: He said, "Get away from him." He said, "I told him I'd be back." And he said, "Now, I'm back."

O'BRIEN: 1989, Louisville, Kentucky, Joseph Westbecker took a rifle to the printing plant where he had worked. He was out on disability for stress and was taking antidepressants when he shot 20 employees.

JAMES ALAN FOX, NORTHEASTERN UNIVERSITY: He felt used up, spit out. He felt his loyalty to the company had not been returned.

CORNELL: He methodically went through the plant shooting people.

O'BRIEN: There is frequently advance planning down to small details.

FOX: Who they're going to kill, where they're going to kill. CORNELL: They plan the weaponry. They even plan what they're going to wear.

O'BRIEN: And sometimes even a dry run. In 1989, Patrick Kirdy (ph) used toy soldiers to plan his attack on a Stockton, California elementary school. He killed five students on the playground and wounded 30 others.

FOX: It may sound good to say that they snap and go berserk, but that's just not the case. These are well-planned executions.

O'BRIEN: Some massacres seem to be inspired by others, large-scale copycat crimes.

CHO: I could have fled. I will no longer run.

(on camera): The package of writings and videos that Cho Seung-Hui sent to NBC News included a reference to Columbine, which was inspired by earlier school shootings.

CORNELL: The boys in Columbine were very clear that they wanted to set a kind of record that they wanted to commit the worst school shooting in history. And they in fact were stimulated by the great media attention given to the prior school shootings.

O'BRIEN: As with Columbine, as with the elementary school in Stockton, as at the printing plant in Louisville, and as with the shootings at Virginia Tech, these massacres often end with the killer taking his own life. So in the throes of depression and rage, is the gunman's outburst of violence about suicide or homicide?

FOX: Their life may be miserable and they take their own life because they don't want to live anymore. It is important to them first to punish all those they hold responsible for their problems and the more people who die, the sweeter the revenge.

SAMAHA: That doesn't make any difference to me anymore. I mean I don't know why. We may never know why.

O'BRIEN: Joseph Samaha lost his daughter Reama (ph) in the massacre at Virginia Tech.

SAMAHA: I'm focused on my child, my family, my friends and reunite her with us. And then, you know, give her a decent burial, a beautiful burial that she deserves.

O'BRIEN: While families grieve, investigators and experts try to get into the mind of the killer, the feelings of persecution, the advanced planning, the mental health issues that drive mass murders to the brink.

And when we come back, one more common denominator, the weapon.

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O'BRIEN (on camera): We now know just how much planning went into the massacre. February 9, Cho walks just across the street from the campus to this pawnshop. He's instantly approved in a background check, and walks out with his first gun. By law, he's got to wait a month before he can purchase a second gun and that's exactly what he does.

UNIDENTIFIED MALE: The Glock 19, a big seller, easy to use, good for self-defense or target practice. When Cho walked into this Roanoke, Virginia gun shop in March, he looked like any of the 100 or so customers who over the past year had stopped in to buy a Glock.

(on camera): Nothing odd about this fellow?

JOHN MARKELL, OWNER, ROANOKE FIREARMS: Not at all. He was very low key.

UNIDENTIFIED MALE: You mentioned clean-cut.

MARKELL: Yes, college student.

UNIDENTIFIED MALE: John Markell, owner of Roanoke Firearms, said, yes, some of the buyers are students. The salesperson that sold the Glock to Cho remembered nothing unusual. More importantly, Cho's paperwork seemed to be in order.

MARKELL: He had three forms of I.D. To buy a handgun, you have to be older than 21 and be a Virginia resident. So he had a driver's license. That established his residency. Then he had his checkbook. The address on his checkbook matched the address on the license. And he had his INS card. So he filled out the paperwork. We called it in to the state police, they ran a background check and he was cleared.

UNIDENTIFIED MALE: Last Monday, three federal agents showed up at Markell's door. The suspect in the Virginia Tech massacre, he was told, had used a Glock 19. The receipt for that gun was found on his dead body. The receipt was from Roanoke Firearms.

(on camera): When they came to you and said that gun that killed so many of these students and professors was purchased here, do you second-guess your profession?

MARKELL: We have to make decisions pretty quick. I was so heartbroken to find out it came from me. I mean I could have done nothing any different. There was no reason for me to deny the sale. We deny sales to people every day. If I smell alcohol on somebody's breath, I'm not going to deal with them. I will stop them for any number of reasons. If people just aren't acting right.

UNIDENTIFIED MALE (voice-over): In the ten minutes it took to make the sale, nobody at Roanoke Firearms had any way of knowing that Cho Seung-Hui had to so terrified his poetry professor that she had kicked him out of her class. No one had any way of knowing he had stalked women. No one would know that in 2005, he had been deemed mentally ill by a judge. Nothing legally would appear on the background check preventing the sale.

MARKELL: He paid by credit card. It's $571.

UNIDENTIFIED MALE: A month before at JND Pawnshop, literally across the street from the Virginia Tech campus, Cho cleared the same background check and picked up a semiautomatic Walther P-22 he ordered over the Internet from this Wisconsin gun dealer.

Two months to acquire the handguns, two hours to inflict horrific carnage. The crime generated international headlines. But among politicians in this heated political season, the surprising lack of outrage at the ease with which this killer got his weapons.

SEN. HARRY REID (D), MAJORITY LEADER: I hope there's not a rush to do anything. We need to take a deep breath.

SEN. JOHN MCCAIN (R), ARIZONA: I do not believe that we should tamper with the Second Amendment of the United States or the Constitution of the United States of America.

UNIDENTIFIED MALE: The National Rifle Association, of course, wholeheartedly agrees the powerful pro-gun lobby did express its condolences. But its written statement said it would not have further comment until all the facts are known.

New York Congresswoman Carolyn McCarthy has seen this all before. The time for waiting, she says, is over.

REP. CAROLYN MCCARTHY (R), NEW YORK: I am not willing to wait another year. I am not willing to wait any longer until there is another shooting.

UNIDENTIFIED MALE: McCarthy made that statement in 1999, shortly after the massacre at Columbine High School in Colorado.

Six years earlier, on a crowded commuter train, her husband was killed and her son severely injured by a mentally disturbed man with a gun. Every year since she entered Congress in 1996, she has introduced some form of gun control legislation. Every year her bill is shot down. Had lawmakers joined with her in the past, McCarthy believes Cho would not have been able to legally buy his guns.

PAUL HEMKE, PRESIDENT, BRADY CAMPAIGN: Here's an individual that if you ask any of his roommates, almost any of his professors, any of the people that knew him, whether this is an individual that should be able to buy a gun, they would have said no.

UNIDENTIFIED MALE: Paul Hemke is president of the Brady Campaign, a group dedicated to ending gun violence. His group grades states on how tightly they control gun sales. Virginia gets a C-minus.

Though John Markell says his gun shop obeyed the law when it sold Cho a Glock, this is not the first time a murder weapon has been traced back to his doorstep. And though he feels great sadness over the events of Monday morning, he says he bears no blame, no guilt. MARKELL: Truthfully, I don't think you can prevent this kind of thing. I can't imagine that he bought that gun specifically for the purpose of shooting all those people. He bought it five weeks ago.

UNIDENTIFIED MALE: Markell was wrong. We now know Cho was planning his attack and the Glock 19 sold at his store would be the main weapon used in the horror at Virginia Tech.

When we come back, the victims.

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O'BRIEN (voice-over): After four days, the family of Cho Seung-Hui broke its silence. Through Cho's sister, they released a statement.

"Our family is so very sorry for my brother's unspeakable actions. We pray for their families and loved ones. We feel hopeless, helpless and lost. My brother was quiet and reserved, yet struggled to fit in. We never could have envisioned that he was capable of so much violence. He has made the world weep. We are living a nightmare."

STEGER: There are really no words that truly express the depth of sadness that we feel. In fact, words are very weak symbols of our true emotions at times such as this.

GEORGE W. BUSH, PRESIDENT OF THE UNITED STATES: By the end of the morning, it was the worst day of violence on a college campus in American history. And for many of you here today, it was the worst day of your lives.

UNIDENTIFIED FEMALE: There you go.

O'BRIEN: This was a final good-bye. Families, friends, fellow students, once united by their undying school spirit now joined in grief, their names and faces reflected the world. They came to learn and they came to teach, 32 faces, 32 victims.

Daniel O'Neil, a graduate student from Lincoln, Rhode Island, played guitar and wrote his own songs. Peruvian Daniel Perez Cueva (ph) had only been in the United States for seven years. The 21-year-old was a champion swimmer and thrived in Virginia Tech's international studies program.

DONALD SMITH, FRIEND: He spoke four languages. And it was always fun just to have a conversation with him.

O'BRIEN: Grad student Juan Ortiz was killed while teaching class. The 26-year-old was from Puerto Rico. He loved salsa dancing and he played in a band with his father.

Civil engineering major Jarrett Lane grew up in Narrows, Virginia and was valedictorian of his high school class. A star athlete, Jarrett also played the trombone

Ross Alemedine (ph), a sophomore from Saugus, Massachusetts, aced French class and was a technology whiz.

VINCENT LEO, NEIGHBOR: He used to fix everyone's computer in the neighborhood if they had trouble.

O'BRIEN: Ryan Clark was raised near Augusta, Georgia, had a 4.0 grade point average and played the baritone horn in the Marching Virginians Band. A resident adviser at the dorm where the killing spree began, Ryan may have been the first to encounter Cho that morning. Just a month short of graduation, he was a source of pride for his twin brother and sister.

BRYAN CLARK, BROTHER KILLED IN VIRGINIA TECH MASSACRE: I'm going to miss watching him share the things he loved to do, watch him share those things with other people.

NADIA CLARK, BROTHER KILLED IN VIRGINIA TECH MASSACRE: I lost a brother, you know. I had two, now I just have one and I lost a friend. I lost part of my heart, you know.

O'BRIEN: They were daughters, sons, best friends.

Maxine Turner, a senior chemical engineering student from Vienna, Virginia, was a red belt in Tae Kwon Do, loved her sorority and the Beastie Boys.

While the rampage was under way, panicked messages were posted on Maxine's MySpace page: "Max, please call us;" "Hey, Max, I hope you're OK." Friends desperately trying to reach the girl they loved.

Erin Peterson (ph) was an only child. The 6-foot tall honor student had a winning smile and helped lead her Virginia high school basketball team to a district championship.

ELIZABETH REED, HIGH SCHOOL TEAMMATE: She always was the one to pump us up before games, top make sure that we were in the right mind set, a positive attitude. And she led us in our team prayer.

GRIFFON: Well, life is so precious. You got to, like, take advantage of everything you've got, live life to the fullest, because you never know when you're going to lose somebody, you know.

O'BRIEN: Freshman Henry Lee from Roanoke, Virginia, was one of 10 children of parents who fled to the United States from Vietnam. Unable to speak English when he arrived, he became a citizen in 1999.

Reama Samaha (ph) came from a close-knit Lebanese-American family. The 18-year-old grew up in Centerville, Virginia, loved dancing.

SAMAHA: Just a terrific little girl. Since she was 4 years old, had dancing shoes on. That was her love.

O'BRIEN: The faces of the victims continue to haunt us.

There's Lauren McCain from Hampton, Virginia, an avid reader who posted her love for Jesus Christ on her face book page.

Master's student Brian Bluhm was from Cedar Rapids, Iowa. He never missed a Hokies football game.

And engineering student, Jeremy Herbstritt, who grew up on a Pennsylvania farm, could fix just about anything.

MICHAEL HERBSTRITT, SON KILLED AT VIRGINIA TECH MASSACRE: That Jeremy was a good boy, a good man, and we're going to love him forever.

UNIDENTIFIED MALE: That's right.

HERBSTRITT: That's what we're going to do, we're going to love him.

O'BRIEN: The faces include five teachers, among them, an Israeli professor who died saving others.

JOE LIBRESCU, FATHER KILLED AT VIRGINIA TECH MASSACRE: I knew that he was going to take action. He was going to do something that's not normal or definitely not something common.

O'BRIEN: Joe Librescu has every reason to admire his father. Professor Livevu Librescu (ph) was shot as he used his body to block his classroom door. His students escaped by jumping from the second- floor windows. Librescu, a holocaust survivor from Romania, died on the very day the world commemorates holocaust victims.

LIBRESCU: He's a hero at a level which I didn't even think my father could be.

O'BRIEN: In the end, the fury of Cho Seung-Hui erased the lives of students and faculty who loved Virginia Tech. But as poet and professor Nikki Giovanni told the mourners and the world, "The heart of this school beats strong."

NIKKI GIOVANNI, POET & PROFESSOR: Because we are strong and brave and innocent and unafraid. We are better than we think and not quite what we want to be. We will continue to invent the future through our blood and tears. Through all this sadness, we are the Hokies. We will prevail, we will prevail, we are Virginia Tech.

CROWD: Let's go Hokies! Let's go Hokies! Hokies! Hokies! Hokies!

(END VIDEOTAPE)

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